Polygenic Factors

Heritability and Risk of Inheritance in Multifactorial Disorders. Heritability may be defined as the additive proportion of total phenotypic variance in a polygenic trait attributable to genetic variation in a population. The values of heritability estimates can range from 0% to 100%. Heritability is a function of genetic factors, environmental factors, and the interaction of genetic and environmental factors. Simple Mendelian traits have a heritability of 100%. Diseases with a heri-tability of less than 100% are inevitably controversial, such as those listed in the previous paragraph.

Other non-Mendelian mechanisms of clinical significance have been recently re-evaluated in terms of new molecular knowledge (the "new genetics"), but are not considered in this review (Anonymous, 1997a, 1997b). These mechanisms include: X inactivation, dosage compensation, epistasis, ectopic recombination, meiotic drive, position effects, microdeletions, other contiguous gene syndromes, chimerism, pleiotrophic homeotic mutations, slippage, and germline mosaicism.

Was this article helpful?

0 0
Supreme Sobriety

Supreme Sobriety

How to Maintain Your Resolution to Be Sober. Get All The Support And Guidance You Need To Be A Success At Sobriety. This Book Is One Of The Most Valuable Resources In The World When It Comes To Turning Your Love For Cooking Into A Money Maker.

Get My Free Ebook

Post a comment